In arthroscopic procedures, access to the interior of a joint is generally provided through narrow cannulas which extend from the surface of the skin, through the intervening tissue, and into the interior of the joint. Arthroscopes and surgical instruments are then passed into and out of the joint space through the cannulas, whereby to enable so-called “keyhole” surgery. See FIG. 1.
It will be appreciated that, in most arthroscopic procedures, at least two portals are used, one to receive the arthroscope (which provides visualization of the internal surgical site) and one to receive the surgical instruments (which are used to perform the surgical procedure at the internal surgical site). In many cases, more than two portals are used.
It will also be appreciated that, depending on the joint, the specific number of portals used, and the exact locations of those portals, may be limited by the anatomy of the patient. By way of example but not limitation, in hip arthroscopy, it is common for two or three portals to be used, i.e., the first two portals being the so-called anterolateral portal (i.e., the “AL portal”) and either the so-called anterior portal (i.e., the “A portal”) or the so-called mid-anterior portal (i.e., the “MA portal”), while the third portal is typically the so-called distal anterolateral accessory portal (i.e., the “DALA portal”).
When the first portal is created into the joint, the portal is generally created without the benefit of any internal visualization (i.e., because there is not yet an arthroscope positioned within the joint).
More particularly, when the first portal is created into the joint, a needle first penetrates from the skin through the intervening tissue structures and into the joint space, then a guidewire is placed through the needle's lumen into the joint space, next the needle is removed, and then a cannula with a blunt obturator is passed over the guidewire, through the skin, and down into the interior of the joint. Once the first cannula has been advanced into the interior of the joint, the obturator and guidewire are removed from the cannula, and then an arthroscope is advanced down the cannula so that its working end is disposed within the joint. Note that the arthroscope is generally releasably attached to the cannula while the arthroscope is deployed in the joint.
With the arthroscope deployed within the interior of the joint, the arthroscope may then be used to provide internal visualization during the creation of subsequent portals into the joint.
More particularly, in hip arthroscopy, the second portal is typically created by using a spinal needle to create a pathway into the joint, and then replacing the spinal needle with a cannula (i.e., in a manner similar to the creation of the first portal, whereby a guidewire is placed through the spinal needle, the spinal needle is removed, and then a cannula is advanced into position over the guidewire).
During creation of the second portal, the surgeon typically uses the arthroscope (which is already positioned within the joint via the first portal) to view the underside of the capsule of the joint and watch for the spinal needle (which is creating the second portal) engaging, and pushing inwardly on, the capsule, thereby creating an inward tenting effect on the capsule. This inward tenting effect on the capsule can then help the surgeon to confirm the proper positioning of the spinal needle relative to the capsule (i.e., to confirm the proper positioning of the second portal relative to the capsule) before the spinal needle is advanced through the capsule, i.e., by pushing harder on the spinal needle so that the spinal needle penetrates through the tough capsular tissue.
However, this inward tenting effect on the capsule can often be difficult to visualize (e.g., it may be a nominal tenting effect which can be difficult to detect vis-à-vis the adjacent capsule tissue), and/or it can be difficult to determine the precise needle location simply by viewing the tented tissue (since the tented tissue may have only a generalized curvature and may not present a distinct apex). Difficulty in visualizing a nominal tenting effect on the capsule can result in the surgeon advancing the spinal needle through the capsule at an undesirable location, potentially piercing and damaging tissue structures within the joint with the spinal needle. When this happens, the surgeon must withdraw the spinal needle from the joint, reposition the spinal needle against the exterior of the capsule, and then make another attempt to establish the second portal into the joint. This repositioning of the spinal needle consumes valuable operating room time. Also, incorrect advancement of the spinal needle into the joint creates the potential for the spinal needle to unintentionally pierce the labrum of the hip joint, or to unintentionally scrape the cartilage on the femoral head of the hip joint, either of which creates trauma to important anatomical structures and is a highly undesirable event.
Therefore, the surgeon needs a better way, when creating the second portal, to determine if the spinal needle is positioned at the correct location prior to piercing through the capsule.